A comprehensive synthesis of liana removal experiments in tropical forests

Abstract

Lianas are a quintessential feature of tropical forests and are often perceived as being poorly studied. However, liana removal studies may be one of the most common experimental manipulations in tropical forest ecology. In this review, we synthesize data from 64 tropical liana removal experiments conducted over the past 90 yr. We explore the direction and magnitude of the effects of lianas on tree establishment, growth, survival, reproduction, biomass accretion, and plant and animal diversity in ecological and forestry studies. We discuss the geographical biases of liana removal studies and compare the various methods used to manipulate lianas. Overall, we found that lianas have a clear negative effect on trees, and trees benefitted from removing lianas in nearly every study across all forest types. Liana cutting significantly increased light and water availability, and trees responded with vastly greater reproduction, growth, survival, and biomass accumulation compared to controls where lianas were present. Removing lianas during logging significantly reduced damage of future merchantable trees and improved timber production. Our review demonstrates that lianas have an unequivocally detrimental effect on every metric of tree performance measured, regardless of forest type, forest age, or geographic location. However, lianas also appear to have a positive contribution to overall forest plant diversity and to different animal groups. Therefore, managing lianas reduces logging damage and improves timber production; however, the removal lianas may also have a negative effect on the faunal community, which could ultimately harm the plant community.

Lianas have a seasonal growth advantage over co‐occurring trees

“…2014, van der Heijden et al. , Toledo‐Aceves , Estrada‐Villegas and Schnitzer ), reproduction (Kainer et al. , Garcia‐Leon et al.…”

Positive effects of liana cutting on seedlings are reduced during El Niño‐induced drought

“…reproduction, regeneration, growth and survival) in aseasonal and seasonal tropical forests alike (Magrach et al., ; Wright, Sun, Pickering, Fletcher, & Chen, ). Although the effect of lianas on forest dynamics has been studied in more seasonal tropical forests (Estrada‐Villegas & Schnitzer, ; Van der Heijden, Powers, & Schnitzer, ), empirical support for the effect of lianas on tree growth and survival remains limited in aseasonal forests of Southeast Asia, which are important biodiversity hotspots of both flora and fauna (Estrada‐Villegas & Schnitzer, ; Myers, Fonseca, Mittermeier, Fonseca, & Kent, ; Wright, Sun, et al., ).…”

“…Lianas affect forest dynamics through impacts on seedlings, saplings and trees (Estrada‐Villegas & Schnitzer, ). Seedling regeneration—both growth and survival—is negatively impacted by liana abundance, especially in gaps where lianas can inhibit establishment of non‐pioneer tree species (Schnitzer & Carson, ; Schnitzer, Dalling, & Carson, ).…”

“…In addition, recent studies have shown positive effects of liana cutting in logged forests (i.e. after felling) for seedling, sapling and tree growth (Campanello et al., ; Estrada‐Villegas & Schnitzer, ; Grauel & Putz, ). However, empirical evidence supporting post‐felling liana cutting practices in Asia remains limited with most studies on lianas in tropical Asia focusing on liana community structure and diversity (Campbell & Newbery, ; DeWalt, Ickes, Nilus, Harms, & Burslem, ; Magrach et al., ; Putz & Chai, ) and pre‐felling cutting (Lussetti et al., ; Putz, ).…”

Do lianas shape ant communities in an early successional tropical forest?

“…Lianas provide key resources to arboreal animals, including food and nest sites (Blüthgen et al., ; Tanaka & Itioka, ). Thus, changes in liana abundance and species composition during succession (Barry, Schnitzer, van Breugel, & Hall, ; Lai et al., ; Letcher & Chazdon, ) should have substantial bottom‐up effects on animal community structure via changes in liana‐based resources (Estrada‐Villegas & Schnitzer, ). Lianas also influence arboreal animal distributions by connecting neighboring treecrowns (Adams, Schnitzer, & Yanoviak, , ; Chiarello et al., ; Yanoviak, ), which are otherwise commonly isolated in space due to “crown shyness” (the tendency for a physical gap to exist between neighboring trees within a forest canopy; Ng, ; Putz, Parker, & Archibald, ).…”